L1 - Introduction and Ocean Basins Flashcards
What so great about oceans?
Where life began and continues to thrive. >70% of earths surface, 99% of all living space, 50 - 80% of all life on earth
In what conditions does life survive in?
Nearly every set of conditions
What does half of the global ocean provide?
Oxygen. Photosynthesis (primary production) by phytoplankton, mangroves, seagrass, green algae
What does the global ocean do?
Sequester (stores) Carbon, regulate the planet’s climate
Why and how do humans depend on the global ocean?
The ocean offers ecosystems services ; fishing, aquaculture, energy, tourism, transport, medicine, coastal defence, culture, wellbeing, physical materials
What are 4 main oceans?
Arctic, Pacific, Atlantic, Indian
What are oceans?
Connected they’re not homogenous
What does the oceans connectivity means?
It means problems are also shared
What is there between oceans and continents?
A geological distinction
What is the clear geological distinction between oceans and continents crust?
In rock, density, thickness, age, colour, elements
Geological distinction between oceans and continents - Oceanic crust?
Basalt (rock), ~3.0 g cm^-3 (density), 5km (thickness), geologically young (<200 My) (age), dark (colour), iron, magnesium (elements)
Geological distinction between oceans and continents - Continental crust?
Granite (rock), ~2.7 g cm^-3 (density), 20-50km (thickness), can be very old (age), light (colour), sodium, potassium, calcium, aluminium (elements)
What does the earth surface comprise of?
Crust, upper mantle, lower mantle, outer core, inner core
What is the density of the continental crust?
lower density
What is the density of the ocean crust?
higher density
What is the lithosphere?
crust & uppermost mantle (tectonic plates)
Where is the asthennosphere is what are its characteristics?
In the upper crust, it is weak and allows plates to move
What was the continent and ocean like 200 million years ago?
one continent and one sea
What is constantly changing?
The surface of the earth is constantly changing and moving - on a very long timescale
What are tectonic plates?
The crust and the upper part of the mantle - the lithosphere, broken into tectonic plates - move as a single unit. Different plates contain continental crust, oceanic crust or both. The lithosphere floats on a denser, more plastic layer of upper mantle (the asthenosphere)
What does tectonic plate movement cause?
Oceanic ridges and trenches
What creates oceanic ridges?
Sea-floor spreading
What causes the formation of deep trenches?
Plate collisions
What geological activity is concentrated at mid-ocean ridges and boundaries?
Volcanoes, Deep-focus earthquakes
